text: # -*- coding: utf-8 -*-
  """
  AR-specific Form helpers.
  """
  
  from django.forms import ValidationError
  from django.core.validators import EMPTY_VALUES
  from django.forms.fields import RegexField, CharField, Select
  from django.utils.encoding import smart_unicode
  from django.utils.translation import ugettext_lazy as _
  
  class ARProvinceSelect(Select):
      """
      A Select widget that uses a list of Argentinean provinces/autonomous cities
      as its choices.
      """
      def __init__(self, attrs=None):
          from ar_provinces import PROVINCE_CHOICES
          super(ARProvinceSelect, self).__init__(attrs, choices=PROVINCE_CHOICES)
  
  class ARPostalCodeField(RegexField):
      """
      A field that accepts a 'classic' NNNN Postal Code or a CPA.
  
      See http://www.correoargentino.com.ar/consulta_cpa/home.php
      """
      default_error_messages = {
          'invalid': _("Enter a postal code in the format NNNN or ANNNNAAA."),
      }
  
      def __init__(self, max_length=8, min_length=4, *args, **kwargs):
          super(ARPostalCodeField, self).__init__(r'^\d{4}$|^[A-HJ-NP-Za-hj-np-z]\d{4}\D{3}$',
              max_length, min_length, *args, **kwargs)
  
      def clean(self, value):
          value = super(ARPostalCodeField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          if len(value) not in (4, 8):
              raise ValidationError(self.error_messages['invalid'])
          if len(value) == 8:
              return u'%s%s%s' % (value[0].upper(), value[1:5], value[5:].upper())
          return value
  
  class ARDNIField(CharField):
      """
      A field that validates 'Documento Nacional de Identidad' (DNI) numbers.
      """
      default_error_messages = {
          'invalid': _("This field requires only numbers."),
          'max_digits': _("This field requires 7 or 8 digits."),
      }
  
      def __init__(self, max_length=10, min_length=7, *args, **kwargs):
          super(ARDNIField, self).__init__(max_length, min_length, *args,
                  **kwargs)
  
      def clean(self, value):
          """
          Value can be a string either in the [X]X.XXX.XXX or [X]XXXXXXX formats.
          """
          value = super(ARDNIField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          if not value.isdigit():
              value = value.replace('.', '')
          if not value.isdigit():
              raise ValidationError(self.error_messages['invalid'])
          if len(value) not in (7, 8):
              raise ValidationError(self.error_messages['max_digits'])
  
          return value
  
  class ARCUITField(RegexField):
      """
      This field validates a CUIT (Código Único de Identificación Tributaria). A
      CUIT is of the form XX-XXXXXXXX-V. The last digit is a check digit.
      """
      default_error_messages = {
          'invalid': _('Enter a valid CUIT in XX-XXXXXXXX-X or XXXXXXXXXXXX format.'),
          'checksum': _("Invalid CUIT."),
      }
  
      def __init__(self, max_length=None, min_length=None, *args, **kwargs):
          super(ARCUITField, self).__init__(r'^\d{2}-?\d{8}-?\d$',
              max_length, min_length, *args, **kwargs)
  
      def clean(self, value):
          """
          Value can be either a string in the format XX-XXXXXXXX-X or an
          11-digit number.
          """
          value = super(ARCUITField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          value, cd = self._canon(value)
          if self._calc_cd(value) != cd:
              raise ValidationError(self.error_messages['checksum'])
          return self._format(value, cd)
  
      def _canon(self, cuit):
          cuit = cuit.replace('-', '')
          return cuit[:-1], cuit[-1]
  
      def _calc_cd(self, cuit):
          mults = (5, 4, 3, 2, 7, 6, 5, 4, 3, 2)
          tmp = sum([m * int(cuit[idx]) for idx, m in enumerate(mults)])
          return str(11 - tmp % 11)
  
      def _format(self, cuit, check_digit=None):
          if check_digit == None:
              check_digit = cuit[-1]
              cuit = cuit[:-1]
          return u'%s-%s-%s' % (cuit[:2], cuit[2:], check_digit)
  
  